The present invention relates to a method of increasing productivity of oil, gas and water wells.
Horizontal and inclined wells are usually directed along the extension of formations (strata) without taking into consideration the influence of rock pressure. This can lead to significant reduction of fluid flows, such as oil, gas and water flows. (1-10). In addition it does not provide a complete embrace of the formation, and in condition of great depths due to compressing ring-shaped stresses as in vertical well it is not always guaranteed that it will be possible to obtain the desired product (27). In these cases it is known to use hydrocracking of formation, chemical treatment and various methods of intensification (1, 6, 9, 11, 12, 4, 13, 14, 15, 9, 16, 5, 17 etc). In many cases the efficiency of these methods is insufficient and their realization is very expensive. The hydrocracking, chemical treatment, point perforation connect with a well bore only a part of formation, for a short time, since the produced spaces are retained under the same rock pressure and after a certain time close again. The utilized methods of intensification do not cover the whole working distance, they are expensive, and their effect disappears after a certain time.
The known intensification methods include the method of unloading with slots (19) which almost fully and permanently removes rock pressure from near-well zone. This increases efficiency of operation of the wells. However this method is not always efficient in horizontal and inclined well where a different mechanism of rock compression takes place, in which orientation of directions of perforation relative to main horizontal stresses, as well as a length and width of the cavities are important. In inclined wells it is known to carry our perforation by the method of slot unloading in a direction of maximum cracking of the near-well zone (20), upwards from the well, which is also not efficient, for example due to “clamping” of the cracks by ring shaped, tangential stresses of double concentration, produced around the perforation channels.
While maximum unloading of a well by a perforation takes place if a plane of a slot is oriented perpendicular to a main stress, the direction of the well is not coordinated with the main stress direction, and the unloading of the well bore will not be optimal. When the plane of the slot is close to maximum horizontal stress, the slot will not work at all and will be immediately compressed by the rock pressure. In the case of a random proper orientation of the perforation, the flow of fluid takes place only at the locations of the perforation (slots, cavities), but not along the whole length of the horizontal or inclined well.